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Are Thorium Reactors Better?


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why Interstate speed limits have not yet been reduced to save fuel consumption

 

—Larv

 

I am not sure if this applies for all cars, but to my knowledge, the faster you go at a constant speed the more fuel you save per mile.

That's why cars/SUVs/trucks w.e all get higher gas mileage at highway/interstate speeds.

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Its not just that the spent fuel cant be used for weapons, Thorium is much more abundant in nature than Uranium and can be put through a cycle of uses that ends up producing much less nuclear waste.  

All of this is very interesting and relevant, especially for the U.S. But as far as I know there are no plans at any U.S. national laboratories or energy sites for building thorium reactors and putti

I'm sorry but you are silly silly people quoting a whole lot of nuclear industry spin media trying to sell "safe" breeding technology. Australia and India have both been trying hard to spin "safe th

Silverslith, you seem to apply more bluster and attitude, not to mention smilies, than sound reasoning to the problem of abating our energy crisis. The most important question about it is this: How do you solve the EC in the most healthful and environmentally friendly way possible? You can rant against nucear power and thorium reactors all you want, but that still doesn't solve the EC. Risk-free energy is hard to find, you know.

 

Just curious: Do you really think that petroleum, coal, natural gas, biofuels, and hydropower are more healthful and environmentally friendly than nuclear power? We have to get down to comparing relative risks of power production to see this problem more clearly. I'll agree with you that rampant capitalism is suspect of spinning the issue, but unless somebody invents a laptop nuclear reactor for powering your home, the guys with the big bucks and purchased politics will have to build the nuclear infrastructure. I sure as hell don't want to build any more coal infrastructure here in America. Furthermore, I am suspicious, for environmental and human health reasons, that those corny biofuels will not solve America's EC. (We gotta feed that corn to our cattle so we can eat 'em!)

 

—Larv

 

 

I thought this thread was "are thorium reactors better"

My answer is NO NO NO from a perspective of researching the Tech thorougly. I don't support corn alcohol or fossil power. Search my posts for the last few days if you want to see the real solutions that are moving fast for clean renewables.

 

Nuclear is up against the wall. They've wanted to get in to breeder reactor technology since the 50's cause they've know since then that the supply of U235 thats economically recoverable is small. Even now there is a huge subsidised fossil fuel contribution to mining and processing that makes rubbish of the claims of "no CO2 emissions" If most of the worlds electricity came from u235 reactors we'd have a decade before it was over.

 

Breeding tech has not been allowed other than in small reactors for weapons Pu for the very real reason that it multiplies the radiological hazard of the nuclear industry by at least 100000 times and much more if we went fully "closed fuel cycle"

Pu breeding from u238 is too hard a sell because its branded as "bomb material" and people know how radioactive Pu is and so realise that one reactor accident would cost lives worldwide. When a spacecraft containing Pu alpha reactors with 40lb of Pu

(theres your briefcase home reactor) burnt up in the atmosphere there was a worldwide cancer spike ~5% over the next decade. Pu has a 24000 yr halflife. The polonium210 we've heard about recently is about 20000 times worse and is pretty average for the isotopes that would need to be handled and separated in large volumes for a breeding or closed fuel cycle technology.

 

Nuclear is trying to brand Thorium as the safe nuclear alterative so that breeding technology can be slipped in under the radar. If they accomplish this it will come out that Pu and a whole lot of far nastier fissionable and breedable isotopes were part of the package "didn't you guys realise that? too late now!". And anyway the U233 fissionable you make from thorium is just as bad as Pu.

 

I just don't think that humans are resposible enough to be allowed to put reactors everywhere that have enough radiation in them to kill everything bigger than a cockroach on this planet if there is one Chernobyl size accident.

 

We'd need to guarantee 100% safety and responsibility only achievable with a high tech culture for a million years to deal with the huge increase of Radioactive stuff on the planets surface that a couple hundred years of "closed fuel cycle" would produce.

Ther has been several chernobyl magnitude accidents at nuclear fuel processing plants in both the US and Russia. If we went closed fuel cycle the risk would be far larger because the mixtures of high actinide breedables (generally high spontaneous Neutron emmission) and fissionables(with very small critical masses) used in fuel rods and needing reprocessing would be very dangerous and far more likely to accidentally "blue flash" (very inefficient chain reaction bomb luckily) as has been all too common in fuel processing plants already. You'd need to simulate every batch on powerful computers, and if someone got some rods mixed up and a reactor went fwoosh it'd be all over.

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Breeding tech has not been allowed other than in small reactors for weapons Pu for the very real reason that it multiplies the radiological hazard of the nuclear industry by at least 100000 times and much more if we went fully "closed fuel cycle"

Specifically what do you mean by "...multiplies the radiological hazard...by at least 100000 times"?

 

Pu breeding from u238 is too hard a sell because its branded as "bomb material" and people know how radioactive Pu is...

OK' date=' just how radioactive active is it? It's alpha radiation, you know.

 

When a spacecraft containing Pu alpha reactors with 40lb of Pu (theres your briefcase home reactor) burnt up in the atmosphere there was a worldwide cancer spike ~5% over the next decade.

Do you mean SNAP 9A? And you say "...a worldwide cancer spike ~5% over the next decade"? Come on, get real. You're passing a brain stone.

 

The polonium210 we've heard about recently is about 20000 times worse...

By what measure?

 

I just don't think that humans are resposible enough to be allowed to put reactors everywhere that have enough radiation in them to kill everything bigger than a cockroach on this planet if there is one Chernobyl size accident.

 

Hysteria. No science. Just hysteria. I'd still rather have a thorium reactor in my back yard than a coal-fired power plant any ol' day.

 

—Larv

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Specifically what do you mean by "...multiplies the radiological hazard...by at least 100000 times"?

In a reactor based on natural actinides:235/238 you have ~100 tons of material with ~4.0 billion years average half life. A reactor based on Pu will have maybe20% Pu239 with 24000 year halflife. So you are going to have at least 166666 /5 = 33333 times as much initial decays there. The side reactions in a reactor configured for breeding will produce a lot of highly active decay chains that multiply this several times. Some of these isotopes have halflifes in micro seconds. others centurys. the days to years scale that most lie within mean that some used nuclear fuel has basically radioactivity in the region of 1 year old = 24000 times as hot gram for gram as Plutonium.

The thorium reactor would need over 30% probably 50%U233 to breed effectively.

u233 has 160000 yr half life but instead of an alpha decay hauling it up at u235 like Pu it goes:

>th229hl7300yrs > Ra225hl15d > ac225hl10d > fr221hl4.9m>at217hl32ms>bi213hl46m>po213hl4.2microseconds>pb209hl3.3hrs.

(ignoring side chains.)

This is governed by the decay rate of U233 so hidden at first by the dyke of Thorium229 it within a few thousand years climbs to 8 events per U233 decay

so 50 tonnes of U233 will produce (24000/160000) * 8 = 1.2 times as much as the equivalent weight of Plutonium after a few thousand years.

 

OK, just how radioactive active is it? It's alpha radiation, you know.

 

Thats the worst type when ingested. alpha has the highest energy impact on cells and dna with ~a million chemical bonds broken by one event in a debris cone. Gamma makes random minor damage on its way outa there and beta is lower energy.

 

 

Do you mean SNAP 9A? And you say "...a worldwide cancer spike ~5% over the next decade"? Come on, get real. You're passing a brain stone.

 

Someone elses brainstone. Show me stats that contradict the ones I've seen.

Of course we can't fingerprint radiation damage so cancer epidemics can't be for example to do with Polonium 210 and 20 other radioisomers at quantities meaning each has the same per unit time decays as the over billion kg of uranium thats been mined. Discarded to blow in the wind and leach into water systems after the Uranium is removed. Thorium has 10 times less of this than uranium but 10 times as much mineral resource so mining enviromental damage is equal in the end. Breeding it will increase the radiological hazard by at least 100000x magnitude over conventional 235 based tech.

 

And in addition reactors configured for breeding ratchet nuclei up the mass scale indescriminally so what the "closed fuel cycle" means is that:

Neptunium 237 hl 210000yrs,

Americium 241 hl 241 yrs,

Plutonium 241 hl 14yrs

Curium 245 hl 8500 yrs,

Californium249 350yrs

Paladium 231 33000 yrs

Uranium 235 700million yrs

plutonium239 24000 years

Curium243 29 yrs

americium243 7400 yrs

berklium 247 1400 yrs

curium247 16 million years (my personal pocket nuke fave)

Californium 251 900 yrs (some other peoples pocket nuke fave easily purchased apparently)

 

Will be all used as fissionables in nuclear fuel rods with multiplication by obvious magnitudes of the radiation risk both immediate and long term.

 

And the stable isotopes with even mass number that I haven't listed will be used for breeding blankets.

 

Everything else will be lagged for decades until its settled down into mostly those more stable isotopes and so is cool enough to move and then reprocessed.

 

Thats the thorium-U233/ U238-plutonium breeding reality.

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In a reactor based on natural actinides:235/238 you have ~100 tons of material with ~4.0 billion years average half life. A reactor based on Pu will have maybe20% Pu239 with 24000 year halflife. So you are going to have at least 166666 /5 = 33333 times as much initial decays there...so 50 tonnes of U233 will produce (24000/160000) * 8 = 1.2 times as much as the equivalent weight of Plutonium after a few thousand years.

OK, thanks. Not a bad reply. But it evades one imporant thing—a meaningful definition of "hazard." From what point of view do you choose to define and measure hazard? From a health physicist's point of view? Nothing you have stated accounts for doses or toxicity or other known radiochemical hazards.

 

Thats the worst type when ingested. alpha has the highest energy impact on cells and dna with ~a million chemical bonds broken by one event in a debris cone. Gamma makes random minor damage on its way outa there and beta is lower energy.

You obviously do not understand the the health-physics aspects of ionizing radiation. Alpha particles' date=' protons, have a very short path before they ionize; and when they do so in critical locations they can pop a DNA molecule, that's for sure. But the plutonium particle must remain in the same place amongst the tissue to do any significant damage. For this reason, plutonium, the major alpha emmitter of concern, has no appreciable effect on the tissues of the digestive tract—it moves along too quickly. And, because it is not absorbed in any appreciable way, the relative risk of DNA mutations occurring from the alimentary passage approaches zero.

 

Please take this anecdote into consideration:

 

I was at a US Department of Energy conference, back in the 1970s, on the environmental and human-health effects of plutonium and other actinides,. There was a guy at the podium; he claimed to be a chemist. He was going on about the biological evils of plutonium, until he finally said: "All chemists agree that plutonium is the most toxic substance known to man." After he completed his delivery and asked for questions, a fellow in the front row stood up and issued a challenge to the speaker: "Next year," he said, "when this conference reconvenes, we will meet back here to conduct a toxicological experiment. I will swallow a tablespoon of pure plutonium, with glass of water to get it down, and you will swallow a tablespoon of pure caffeine, with a glass of water to get it down. Then we will leave it to the conferees to compare the toxicological effects. The winner will be the one who survives the ordeal."

 

The challenge was refused, and wisely. The challenger knew that a tablespoon of pure Pu with a glass of water would go right through like milk of magnesia, and probably without the side effects. One the other hand, a tablespoon of pure caffeine would be enough to kill a man, if not an elephant.

 

This is not to say that an [i']inhaled[/i] plutonium particle would have the same effect. Indeed, it could cause lung cancer if it remained long enough in aveolar tissue, increasing the chance of ionizing near enough to DNA to cause an cancerous mutation.

 

—Larv

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OK, thanks. Not a bad reply. But it evades one imporant thing—a meaningful definition of "hazard." From what point of view do you choose to define and measure hazard? From a health physicist's point of view? Nothing you have stated accounts for doses or toxicity or other known radiochemical hazards.

 

 

You obviously do not understand the the health-physics aspects of ionizing radiation. Alpha particles, protons, have a very short path before they ionize; and when they do so in critical locations they can pop a DNA molecule, that's for sure. But the plutonium particle must remain in the same place amongst the tissue to do any significant damage. For this reason, plutonium, the major alpha emmitter of concern, has no appreciable effect on the tissues of the digestive tract—it moves along too quickly. And, because it is not absorbed in any appreciable way, the relative risk of DNA mutations occurring from the alimentary passage approaches zero.

 

Please take this anecdote into consideration:

 

I was at a US Department of Energy conference, back in the 1970s, on the environmental and human-health effects of plutonium and other actinides,. There was a guy at the podium; he claimed to be a chemist. He was going on about the biological evils of plutonium, until he finally said: "All chemists agree that plutonium is the most toxic substance known to man." After he completed his delivery and asked for questions, a fellow in the front row stood up and issued a challenge to the speaker: "Next year," he said, "when this conference reconvenes, we will meet back here to conduct a toxicological experiment. I will swallow a tablespoon of pure plutonium, with glass of water to get it down, and you will swallow a tablespoon of pure caffeine, with a glass of water to get it down. Then we will leave it to the conferees to compare the toxicological effects. The winner will be the one who survives the ordeal."

 

The challenge was refused, and wisely. The challenger knew that a tablespoon of pure Pu with a glass of water would go right through like milk of magnesia, and probably without the side effects. One the other hand, a tablespoon of pure caffeine would be enough to kill a man, if not an elephant.

 

This is not to say that an inhaled plutonium particle would have the same effect. Indeed, it could cause lung cancer if it remained long enough in aveolar tissue, increasing the chance of ionizing near enough to DNA to cause an cancerous mutation.

 

—Larv

 

If you ate as much as 100 millionths of a gram of plutonium you would almost certainly die according to Ld50 ratings which are extrapolated from animal studies and have some variance depending on who was doing the study . Its highly chemically reactive and soluble unless ceramicised by high temperature. It is biochemically concentrated in many organs and bones and studies such as Irish sea oysters and other marine life (google: irish sea plutonium for 178000 pages of many studies) have indicated it is powerfully concentrated by the oceanic foodchain.

If you ate a teaspoon of its pure metallic form the result would be more serious but simular to eating a teaspoon of potassium metal. Your stomach would explode spectacularly.

 

I think you are confusing the properties of Alpha particles (helium nuclei with typically 5 MeV of energy) and conventional helium 2+ ions. The typical chemical bonding energy is a few eV, and dna bonds are at the low end of the bond energy scale. So an Alpha event can ionise over half a million bonds and create something like that amount of exotic free radicals and ions with powerful chemical reactivity.

While studies from the Nuclear Industry abound with claims that a small amount of radiation is health giving because it stimulates natural radiation defences these are highly controversal and its worth comparing them to claims of the "health giving and energising properties of radioactive hot springs" that was a big fad 100 years ago.

I have heard of from reputable academics but not been able to find published, Large population epidemilogical studies done in the 1920s on RA bathers that were supposed to have shown that the Cancer result of spreading the same dose over a larger population was higher (eg/ if you gave an ld50 to 10 people it'ed kill 5. Give the same total quantity given to the 10 to 1000 and it would kill more than 5). Thats not the sort of thing the nuclear industry would want to admit So there may well be a response in stimulating cell repair mechanisms but this actually makes things worse for large scale trace contamination of the enviroment as extra deaths are occuring though not linkable by physical evidence to any particular source.

In any event there appears to be a growing consensus that no low level of enviromental radiation is safe and that any increase over the natural background has a blood cost.

 

I made an error above regarding snap9A. It was Pu238 not Pu239. Made by u235 + n > u236 + n >np237 + n > Pu238 as a normal consequence of u235 reactors it has 87 year half life. My reference was from Dr Helen Caldicots book "the new Nuclear Danger" and I believe she referenced cancer studies but it was 5 years ago I read it and can't recall. Anyway googling "plutonium Re-entry" will give you 144000 pages with all sides expressing their opinions. You can read about a number of other some much larger Pu238 wads reentering uncontrolled. I think Snap9a was the only one to burn up in the atmosphere. They're designed to survive splashdown now but not smashdown.

Personally, If a reactor accident could release twice as much radiation as another reactor I'd say its "potentially" twice the Hazard. You might say that the reactor could be safer but when its 4-5 orders of magnitude higher in RA then safer doesn't reduce the "risk factor" much. Reprocessing fuel in the "closed fuel cycle" is incredibly complex relative to NU enrichment so has far higher chance of accident. And a much higher potential release of RA. So risk factor multiplied.

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An interesting comparison is the relative radioactivity of U238 and Pu238.

4 500 000 000 yrs/ 87yrs= 51724138

 

so the initial radioactive decays of 8000 ton of uranium emitted by coal power plants /yr is equal to the initial decays of 155 grams of Pu238 from re-entry burnup.

 

The Pu238 would be far more effective in adverse health consequence since its strongly retained by the body chemically. And concentrated by the foodchains.

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silverslith, you are not well advised on plutonium toxicity. Maybe I can help to improve your understanding of it.

 

I’ve worked in national laboratories where they fed high doses of different chemical compounds of Pu—and I mean dosages and chemical configurations that were unrealistic in any natural or accidental setting—to cows without adversely affecting their health, their beef, or the milk they produced. Researchers also did the same to chickens and observed no appreciable effects on either the birds or their eggs. I, along with my colleagues at one national laboratory, have performed similar research to investigate Pu effects and accumulations in fish. My research group generally concluded:

 

1. No adverse effects whatsoever occurred in the fish from even the highest concentrations of Pu known to occur in any nuclear-waste pond in the world.

 

2. If a human ate one pound of the most contaminated fish (gut contents included) everyday for 75 years he would receive less than the maximum permissible dosage from Pu (and olther actinides) specified by rigorously appointed human health standards.

 

And, silverslith, you would do well to read this rather famous paper "The Myth of Plutonium Toxicity" by Bernard R. Cohen, a highly respected health physicist:

 

Plutonium is constantly referred to by the news media as "the most toxic substance known to man.'' Ralph Nader has said that a pound of plutonium could cause 8 billion cancers' date=' and former Senator Ribicoff has said that a single particle of plutonium inhaled into the lung can cause cancer. There is no scientific basis for any of these statements as I have shown in a paper in the refereed scientific journal Health Physics (Vol. 32, pp. 359-379, 1977). Nader asked the Nuclear Regulatory Commission to evaluate my paper, which they did in considerable depth and detail, but when they gave it a "clean bill of health'' he ignored their report. When he accuses me of "trying to detoxify plutonium with a pen,'' I offered to eat as much plutonium as he would eat of caffeine, which my paper shows is comparably dangerous, or given reasonable TV coverage, to personally inhale 1000 times as much plutonium as he says would be fatal, or in response to former Senator Ribicoff's statement to inhale 1000 particles of plutonium of any size that can be suspended in air. My offer was made to all major TV networks but there has never been a reply beyond a request for a copy of my paper. Yet the false statements continue in the news media and surely 95% of the public accept them as fact although virtually no one in the radiation health scientific community gives them credence.[/quote']

 

Does any of this help to ease your anxious mindset concerning the evils of Pu?

 

—Larv

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What do you think of this article with its potted history of thorium?

Resource Investor - Uranium - Thorium: An Alternative to Uranium, 2007 Update

Thorium although it had a relatively abundant fissile isotopes was immediately relegated to a back seat, because its properties dictated that although it could be used to manufacture a nuclear reactor it could not be used to or be useful in the construction of a fission weapon!

 

Thorium powered reactors were designed and built during and just after World War II to test power an ocean going vessel and to create the first civilian use only nuclear power plant at Shippingport, Pennsylvania.

 

Early proponents of civilian nuclear power did not want to manufacture devices from which weapons grade materials (i.e., highly enriched uranium or the new synthetically produced and highly fissile plutonium) could be easily extracted, because at the beginning of the �atomic age� it was believed that only a massively expensive and sophisticated industrial nation could afford to build the enormously costly and limited use base to produce weapons grade materials.

 

So, the development of thorium-based nuclear reactors was continued for a while in parallel with those using uranium and/or plutonium-based technologies. Then a series of intelligence underestimates and political errors combined to terminate government support and funding of what parallel development there was and to propel uranium to the first and only place in the race.

 

This is interesting too

FIN24 : Empowering Financial Decisions

Seven reasons to back nuclear power

and

A solution that would make everyone happy would be the development of thorium nuclear reactors, which can produce electricity without making the sort of enriched uranium that can be used in a bomb. Thorium reactors are a 50 year old technology, well within the reach of these countries, given Russian assistance.
Lifeboat Foundation Blog » Saudi Arabia and Russia Ready to Cooperate on Nuclear Energy
There are 441 operational nuclear power reactors around the world today, with the IAEA reporting that 130 new nuclear power plants are either being built or are in the planning stages. These are conservative estimates, with the actual number of new plants likely to be much higher.

Fronteer Development Sizzling Hot in Gold & Uranium - Seeking Alpha

 

Some of the chemistry:-

Energy from Thorium

 

A weblog devoted to the discussion of thorium as a future energy resource, and the machine to extract that energy--the liquid-fluoride nuclear reactor.

Saturday, April 22, 2006

Welcome and Introduction

This weblog is intended to be a location for discussion and education about the value of thorium as a future energy source. Despite the fact that our world is desperately searching for new sources of energy, the value of thorium is not well-understood, even in the "nuclear engineering" community.

Energy from Thorium: Welcome and Introduction

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Thorium although it had a relatively abundant fissile isotopes was immediately relegated to a back seat, because its properties dictated that although it could be used to manufacture a nuclear reactor it could not be used to or be useful in the construction of a fission weapon!

 

See I get this horrid jarring sense of "Are they trying to steal our reality?.." when I read a paragraph like that.

Potentially fissile isotopes of Thorium:

Th 225 half life 8.7min

Th 229 hl 7000 years (just cool enough to be possible but probably not enough neutron yield, Very low concentrations in nature)

Th 233 hl 22min

Th 227 hl 19days

Th 231 26hrs

Th 235 7.2min

 

None of these with any recoverable or even detectable natural occurance. So its not possible to use thorium as fission fuel other than the decay product of U233- Th229 and that may not release enough neutrons to be usable.

 

There was a U233 Bomb detonated in 1955.

 

Operation Teapot

 

Test: MET

Time: 19:15 15 April 1955 (GMT)

11:15 15 April 1955 (PST)

Location: Nevada Test Site (NTS), Frenchman Flats

Test Height and Type: 400 Foot Tower Shot

Yield: 22 kt

 

 

MET stands either for "Military Effects Test" or "Military Effects Tower" (according to Frank Shelton). This was a LASL test of a composite U-233/plutonium bomb core (the first test by the U.S. to use U-233) in a Mk 7 HE assembly. The 30 inch diameter spherical implosion system weighed 800 lb.

 

The primary purpose was to evaluate the destructive effects of nuclear explosions for military purposes. For this reason, the DOD specified that a device must be used that had a yield calibrated to within +/- 10%, and the Buster Easy device design was selected (this test gave 31 kt and used a plutonium/U-235 core). LASL weapon designers however decided to conduct a weapon design experiment with this shot, and unbeknownst to the test effect personnel substituted the untried U-233 core. The predicted yield was 33 kt. The actual 22 kt was 33% below this, seriously compromising the data collected.

 

 

ArmsControlWonk: Safeguarding Breeder Reactors

Jeffrey Lewis wrote:

“I think some of you are overlooking the fact that the Indian breeders are designed to utilize thorium in the place of uranium.”

 

Its somewhat more complex than that.

 

The 500 MWe Indian PFBR will have a core loaded with TWO TONS of plutonium. The core will contain an average of ~25% plutonium and 75% uranium (both as oxides)

 

This reactor will have two separate breeding blankets. One will be rods of thorium to breed U233 in (the radial blanket), and the other will be composed of depleted uranium (in the outer 40% of each core fuel pin) to breed Pu239 (the axial blanket).

 

The reactor will thus “launder” the MOX plutonium into supergrade Pu AND produce vast amounts of U233 bomb material. The blanket supergrade Pu may also be blended with large amounts of the core’s reactor-grade Pu, producing enormous amounts of ordinary weapons-grade Pu – essentially a superpower-sized atomic arsenal from a single core load.

 

The U233 produced from the thorium blanket is a superb bomb material. A weapon can be created just by DROPPING a subcritical mass from a few feet onto another subcritical mass.

 

It is important to keep the U232 (a hard gamma emitter) minimized for health reasons, but in the FBR it is easy to keep it under 5 ppm.

 

yale

— Yale Simkin · Feb 1, 06:00 PM ·

 

The "drop one piece on to the other" bit is because the spontaneous neutron emissions in U233 are so low that it takes a while for the chain reaction to exponentiate.

Thats why Pu requires faster assembly of a critical mass than u235.

 

Micronukes (Carey Sublette)

 

A general rule is that highly fissile isotopes have odd-numbered masses

(and also have low spontaneous fission rates), while isotopes with even

numbered masses are much less fissile, and have high spontaneous fission

rates. Thus U-233 and U-235 are fissile, while U-238 is not; and U-238 has

a spontaneous fission rate more than an order of magnitude higher than

either of the two odd isotopes.

 

 

NTI: Securing the Bomb: Technical Background: Weapons Design and Materials

 

 

Table 1: Properties of Nuclear-Explosive Nuclides says this: although the Spontaneous fission rate and neutron capture rates of u233 appear classified in the US and are a little hard to verify. note that in an enriched 235/238 bomb its the magnitude higher Spontaneous fission rate of the U238 that is the "match" that sets off the chain reaction. So a 12% u233 in u238 would initiate faster than a pure U233 critical mass.

 

ISOTOPE and critical mass:

 

U-233 15kg

U-235 50kg

Pu-239 10kg

 

The properties of U-233 as a nuclear explosive would seem to make it quite attractive to bomb-makers. Its bare-sphere critical mass is very similar to that of delta-phase plutonium-239, which is to say it's only 50 percent greater than that of alpha-phase plutonium-239 and about one third that of uranium-235. (Its greater reactivity compared to that of U-235 is reflected in the fact that a mixture of only 12 percent U-233 in U-238 is considered weapon usable, as opposed to the corresponding figure of 20 percent for U-235.) The rate of neutron generation from spontaneous fission in U-233 is low enough, moreover, to permit its use in the simpler gun-type weapon designs as well as in implosion designs; and its decay heat is one sixth that of Pu-239. Its gamma-ray dose rate is in the same range as that from weapon-grade plutonium.
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Plutonium health effects:

Statement of Chris Busby

 

...Since 1997, I have been supported by the Government of the Republic of Ireland to investigate the incidence of cancer in populations living near the Irish Sea. I have been able to use two datasets, that of the Wales Cancer Registry 1974-89 and that of the Irish Cancer Registry 1994-1996. For both countries, small area data were used to define cancer risk by distance from the sea. This risk was calculated as Standardised Incidence Ratio which is defined as: Observed number of cancer cases divided by the expected number of cancer cases. This latter was calculated from the appropriate national age specific rates and the small area census populations.

Results indicated quite specific effects existed in relation to proximity to the sea. The highest cancer risks were in the population living within 1km of the sea, and were driven by seaside towns close to large areas of radioactively contaminated intertidal sediment. In Wales, an example was the town of Bangor, close to the mud bank called the ‘Lavan Sands’ where concentrations of Caesium-137 and Plutonium-239 had been regularly measured by government survey teams. The origin of this material was Sellafield, 70 miles to the north. The relative risk of childhood cancer in Bangor was over ten, based on national averages. This means that some cause existed there which resulted in ten times more cancer in children than there would be in an another equivalent town where no such cause existed. There were also significantly elevated levels of breast cancer, leukemia, colon cancer and all cancers. The risk trend with distance from the sea was quiet specific, falling off sharply inside the first few kilometres and then flattening out. ...

 

This collection of News media articles 1986/87 detailing how "safe" the nuclear industry actually is is disturbing :

LET THE FACTS SPEAK

 

I actually don't think that the nuclear industry would cospire to exagerate the toxicity and radiologic hazard of Pu.

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Plutonium health effects:

Statement of Chris Busby

 

...Since 1997, I have been supported by the Government of the Republic of Ireland to investigate the incidence of cancer in populations living near the Irish Sea. I have been able to use two datasets, that of the Wales Cancer Registry 1974-89 and that of the Irish Cancer Registry 1994-1996. For both countries, small area data were used to define cancer risk by distance from the sea. This risk was calculated as Standardised Incidence Ratio which is defined as: Observed number of cancer cases divided by the expected number of cancer cases. This latter was calculated from the appropriate national age specific rates and the small area census populations.

Results indicated quite specific effects existed in relation to proximity to the sea. The highest cancer risks were in the population living within 1km of the sea, and were driven by seaside towns close to large areas of radioactively contaminated intertidal sediment. In Wales, an example was the town of Bangor, close to the mud bank called the ‘Lavan Sands’ where concentrations of Caesium-137 and Plutonium-239 had been regularly measured by government survey teams. The origin of this material was Sellafield, 70 miles to the north. The relative risk of childhood cancer in Bangor was over ten, based on national averages. This means that some cause existed there which resulted in ten times more cancer in children than there would be in an another equivalent town where no such cause existed. There were also significantly elevated levels of breast cancer, leukemia, colon cancer and all cancers. The risk trend with distance from the sea was quiet specific, falling off sharply inside the first few kilometres and then flattening out. ...

 

This collection of News media articles 1986/87 detailing how "safe" the nuclear industry actually is is disturbing :

LET THE FACTS SPEAK

 

Thorium232 has another problem relative to U238 as a breeding material. While U238+ n > U239 hl 23min > Np239 hl 2.3days> pu239. So after a month or so very much most of the Np239 has decayed into Pu239.

Because Th232 + n > Th233 hl 22min > Pa233 hl 27 days> U233 it will need to be lagged for a couple of years for the high beta emmission from Pa233 to subside and for it to settle down as U233. Even after 20 half lifes it would have reduced by only 1 million times when the U233 is 160000yr/ 0.07yr = 21 million times less active than the same number of Pa233. So its going to take over 24 halflifes of Pa233 = 648days for the radiation component of the Pa233 to fall as low as the Pu magnitude of the U233.

Off to watch Stargate:)

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On that biological accumulation of Pu. I've been perusing some studies on marine life in the Irish sea and Russian north coast and I'm happy to admit that "strongly accumulated by the foodchain" is too strong a statement. It seems some marine algae pick it up well and filter feeders such as mussels, cockles, clams and particularly scallops because they live in the ooze pick it up from them. Levels in higher predators don't seem to get larger per kg so they would seem to get rid of it reasonably well. Levels of other fission fractions, neutron activation products, and Polonium 210 from uranium decay are apparently of greater concern. So devilish properties of Pu probably aren't a tick for thorium.

 

There is a lot of talk about U232 contamination or intentional spiking being a good way to ensure U233 from Thorium is difficult to make bombs out of. Eg:

Energy from Thorium: Denaturing Thorium with Ionium

 

this is because Th232+ n does not always make th233 >u233. Sometimes it emits two neutrons instead >th231>pa231 + n > u232

or another way: U233+n > u232 + 2n

 

Theres a good little diagram on that blog with some of the other breeding pathways that happen. Several good diagrams and tables

 

Anyway so this idea is that you intentionally make your thorium more radioactive with this u232 hl 69 years(on the blog it says 78), even so far as deliberately making it from the thorium230 in mine tailings(nice chart showing all the relative quantities of Radionuclei in Uranium mine tailings). May have the advantage of stopping the tailings radioactivity blowing around as it spends hl3.8 days as Radon gas. Stirring them up again would be worse.

This because the Extra radioactivity means that the "particularly penetrating gamma rays" of Tl208 further down the decay chain will fry the electronics of any bomb someone tries to make. Apparently:

Weapons, especially those that want to be launched on ICBMs, can't afford thick heavy gamma shielding around their fissile cores to protect the sensitive electronics that trigger detonation. So fissile material for weapons needs to emit easily-shielded radiation. Plutonium-239 and uranium-235 both fit the bill. Uranium-233 contaminated with uranium-232 does not.

 

Hmmm. All modern bombs designs tend to use a "tamper" consisting usually of U238 in a 10cm thick hollow sphere around the core. This to reflect neutrons back and reduce the critical mass, as well as containing the reaction as long as possible (briefly) by brute inertia against the 1000000 atmosphere pressure being generated. Interestingly the fast neutron fission in the U238 tamper can provide more energy than the highly fissiles in the core. Gamma rays will not penetrate 1/20 of this. Or 10mm of lead. This is probably the easiest engineering problem in nuclear fission I have ever seen. You don't even need any electronics.

Anyway making it required by law to spike your u233 fuel with enough u232 to make it 10 or 100 times more radioactive than its already nasty levels just does not seem logical to me and there appears no sense in the non proliferation argument. More logical is "if you have a weakness, say its your strength" with regard to the problem of not being able to avoid U232 contamination and the corresponding boost in radioactivity.

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On that biological accumulation of Pu. I've been perusing some studies on marine life in the Irish sea and Russian north coast and I'm happy to admit that "strongly accumulated by the foodchain" is too strong a statement...

Bear in mind that biological life did not encounter PU or any other actinide along the course of its evolution. It is too large and too strange an atom for biochemistry to assimilate; no apprceiable uptake, storage, or metabolic association. No extreme toxicity either, but its ionizing radiation can cause DNA mutations if a Pu particle sticks around the same tissue long enough. For that reason, the inhalation of tiny Pu particles is a hazard to the health of lung tissue.

 

Let me ask you this: What about the health hazards from other energy technologies? Have you compared the risks from the thorium energy production cycle against those of other energy production cycles? I'll be more eager to continue this discussion with you when you have a better understanding of the relative risks of energy production. Take a look at the relative risks of coal and oil energy production cycles, for example.

 

The one relative risk that always interested me was the relative risk of ultraviolet radiation—sunshine, in particular. Once I attended a Downwinders protest of radiactivity blowing off the Hanford Site, in eastern Washington, whereat most of the protestors had dark tans from either farming or just sunning. They needed to know about relative risks.

 

—Larv

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Bear in mind that biological life did not encounter PU or any other actinide along the course of its evolution. It is too large and too strange an atom for biochemistry to assimilate; no apprceiable uptake, storage, or metabolic association. No extreme toxicity either, but its ionizing radiation can cause DNA mutations if a Pu particle sticks around the same tissue long enough. For that reason, the inhalation of tiny Pu particles is a hazard to the health of lung tissue.

Other than Uranium and Thorium of course. Chemistry of actinides does vary too. Or they couldn't be seperated by chemical processes. There is certainly some heavy metal toxicity involved. Even if they are removed and excreted (and the main mechanisim for this is probably when a cell is killed and removed with its contents) the reproductive cells cop a big dose from the proximity to the urinary tract.

 

Let me ask you this: What about the health hazards from other energy technologies? Have you compared the risks from the thorium energy production cycle against those of other energy production cycles? I'll be more eager to continue this discussion with you when you have a better understanding of the relative risks of energy production. Take a look at the relative risks of coal and oil energy production cycles, for example.

No way I'm going to argue for Fossils. However at least the only long term effect they can have is climate change. Theres plenty of energy technologies that don't have the potential for major enviromental impact. Unfortunately Oil and Nuclear are the only ones that allow a monopoly on energy supply to be purchased and defended by big money. Thats why Oil won over biofuels 100 years ago. Henry Ford was on the biofuels side bigtime.

 

 

The one relative risk that always interested me was the relative risk of ultraviolet radiation—sunshine, in particular. Once I attended a Downwinders protest of radiactivity blowing off the Hanford Site, in eastern Washington, whereat most of the protestors had dark tans from either farming or just sunning. They needed to know about relative risks.

 

—Larv

 

The UV radiation down here is very serious. Sunburn in 10min even if you are not very succeptable. I know chemists in the paint industry that have told me that paint here is fried at 6 - 10 times the rate in the UK.

Still, hiding from the sun has caused far more liver cancer from vitamin D deficiency than the skin cancers its stopped. You've got to take suppliments and hide from the sun it seems.

I weighed into this debate because it was obvious that someone was needed to argue the negative. I've been taking it as "Is thorium better than other Nuclear techs". I've spent too much time here this last week( too the detriment of my business) and I've covered most all I want to say. So I'd welcome anyone else prepared to step in and take the reins for the contra.:)

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...I weighed into this debate because it was obvious that someone was needed to argue the negative. I've been taking it as "Is thorium better than other Nuclear techs". I've spent too much time here this last week( too the detriment of my business) and I've covered most all I want to say. So I'd welcome anyone else prepared to step in and take the reins for the contra.

silverslith, I appreciate your contribution. These kinds of discussions need to take place to get at some of the deeper and more important issues surrounding this war-provoking energy crisis. The sad reality is that our future energy demand will ONLY increase, and probably exponentially. There's a lot of hype and hysteria surrounding energy technologies. We've got to bust through all that to get a handle on the EC. Forums like this one are good places to hash it out.

 

—Larv

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